from the GNU version of the Collaborative International Dictionary of English

from The Century Dictionary and Cyclopedia

To harden; confirm in resistance; make obdurate.

Hardened, especially against moral influences; wickedly resisting.

Hard-hearted; inexorable; unyielding; stubborn.

Inflexible; stiff; harsh.

Synonyms Obdurate, Callous, Hardened. These words all retain the original meaning of physical hardening, although it is obsolescent with obdurate. In the moral signification, the figure is most felt in the use of callous, which indicates sensibilities to right and wrong deadened by hard treatment, like callous flesh. Hardened is less definite, it being not always clear whether the person is viewed as made hard by circumstances or as having hardened himself against better influences and proper claims. Obdurate is the strongest, and implies most of determination and active resistance. See obstinate.

Etymologies

Middle English obdurat, from Late Latin obdūrātus, past participle of obdūrāre, to harden, from Latin, to be hard, endure : ob-, intensive pref.; see ob- + dūrus, hard; see deru- in Indo-European roots.

(American Heritage® Dictionary of the English Language, Fourth Edition)

In their valuation of the distribution of grace, theologians distinguish somewhat sharply between ordinary sinners (among whom they include habitual and relapsing sinners) and those sinners whose intellect is blinded, and whose heart is hardened, the so-called obdurate sinners (obcaecati et indurati, impaenitentes).

He thrilled even now at the recollection of the Hadendowas leaping and stabbing through the breach of McNeil's zareba six miles from Suakin; he recalled the obdurate defence of the Berkshires, the steadiness of the Marines, the rallying of the broken troops.

Demonstrating the kind of obdurate thickness most commonly found in that foreign land known as Washington, Augusta County supervisors - five of them at least, the Gang of Six having been diminished by one - acted Wednesday in accordance with an inevitability predetermined by them.

'' obdurate '' position was allowing Pakistanâ€ ™ s militaristic constituency to up the ante and build up a hostile atmosphere at the expense of its peace-seeking civil society, undermining US goals in Afghanistan.

"And if you remain callous and obdurate, IShall perish as he did, and you will know why,Though I probably shall not exclaim as I die,'Oh, willow, titwillow, titwillow!'"– from "On a tree by a river a little tom-tit" (Sung by Ko-Ko in The Mikado)